Electrical musical instrument



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ELECTRICAL IUS ICAL IN STRUIEN'I' Filed Jan. 19, 1954 is Sheets-Sheet 11 72 ROTOR 5 sk m 3Q Patented Apr; 24,

ELECTRICAL MUSICAL INSTRUMENT Laurens Hammond, Chicago, Ill.

1934, Serial No. 707,280 I Application January 19,

74 Claims.

duced by synthesis of the fundamental tone with J various proportions of its harmonics.

I am aware that various attempts have been made in the past to produce an instrument of this but as far as I have knowledge, none of these attempts accomplish the desired result 10. because of will hereinafter be more fully discussed. 16 I It is a well known fact that any sustained musical soundcan be analyzed into sine wave complitude and various amplitudes of different harmonies of the fundamental. It has been found that in most musical tones the predominant harmonies are those of the lower frequencies, and that harmonics above the eighth have very little effect in characterizing the tone, especially in the middle and upper registers of a higher order would lie above the range of audibility.

Thus most musical tones may be produced by definite combinations of\ the fundamental tone with various proportions of the first eight hars monies I iihe instrument of my invention employs the tempered musical scale not only in the production of the fundamentals but in the production of the various harmonics. As a result any desired chords may be played ble beats. It is thus the primary object of my invention A0 to provide an electrical instrument for the produetion of musical tones upon which any desired musical composition may be played. Incident to this broad object of my invention. are numerous other objects, the attainment of which contributes materially to the'achievement of the primary object. These objects appear more fully in the accompanying specification, and include the following: J

(l) To provide an improved means for gene'i) crating a plurality of currents of'diflerent'frequencies capable of being translated into musi -cal sounds.

l2) To provide improved means for driving such generators at a constant speed. A

515'. ('3) To provide improved circuits by which cupwhere harmonics without causing audi- Y rents from various or synthesized.

generators may be combined (4) To provide improved means for eliminating the in the (5) To provide noise produced upon completing and breakthe various circuits, sometimes referred to as' key thump or key click" noise.

an improved electrical circuit wherein a plurality of currents from dlfierent sources may be combined additively without appreciable cancellation or subtraction.

(6) To provide an electrical circuit in which selected proportions of electrical energy derived from sources 0 bined.

different frequencies may be com- I (7) To provide selective means for changing 7 the quality of the tones produced by the instrum'ent.

(8) To provide selective means for changing the drawn relative proportions of the electrical energy from the generators of the fundamental and the various harmonics thereof.

(9) To provide selective means for simultaneously determining the quality of all of the tones.

produced upon depression of the keys of a manual.

of a plurality of preselected qualities.

(11) To provide means for easily changing said preselected qualities of tone.

(12) To provide rents produced by for due

(14) To provide ing means for adjusting the curthe generators to compensate unavoidable defects in the means ultilized to .translate the currents into sound.

(13) To provide of generators of different frequencies which rean arrangement of a plurality to es inductive coupling between the generators.

an improved means for drivthe generators at the different speeds required for the generation of the currents of different frequency. (15) To provide improved means for producing tremolo effects.

(16) To provide improved methods of wirmg the duetors resi (17) To provide whi (18) To provide her changing the quality of the tones produced by playing upon the instrument wherein a number of the conserve as a means for introducing high stances into the circuit.-

an instrument of the type ch is relatively light in weight and is portable.

an instrument having a numof-key manuals with improved meansfor 105 different manuals.

(19) To produce similar generators for a plurality of different frequencies-in which compensati on may readily be made to cause the currents 11o produced by the generators when translated into sound to be of equal volume.

() To provide a plurality of generators of currents of different frequencies in which a single' countershaft comprising a plurality of articulated sections is utilized for driving all of the generators. l

(21) To provide a bank of generators for currents of different frequencies in a plurality of flexibly connected units, eachunit including a plurality of generators of frequencies which are exact multiples of one another and each unit being shielded from the remaining units.

(22)To provide a plurality of generators for producingcurrents of different frequencies, made up of a plurality of similar units 'in which the rotor shafts of successive units are staggered relative to one another so that the rotor shafts of adjacent units may have a bearing in common.

(23) To provide an improved resilient driving 6 connection between the synchronous motor and the generators.

(24) To provide an improved gearing arrange- ,ment for driving the rotors of the generators at the required speed.

(25) To provide an instrument in which chords may be played and in which all of the electrical current of the same frequency. whether utilized in the various tones as fundamentals or as harmonies is derived from a common source.

(26) To provide an instrument in which diminution of the output derived from a given generator is obtained by a method which decreases the impedance of the output circuit.

(2'7) To provide an instrument having a plurality of keyboards in which there is a duplication of tone range and in which tones of different quality may be controlled by the different keyboards, in such manner that the depression of corresponding keys on two or more keyboards will result in a true combination of the individual tones produced thereby, without substantial energy loss.

- (28) To provide an instrument having a plurality of alternating current generators of different frequency capable of generating relatively strong currents and by suitable resistances decreasing the actual currents utilized to a relatively small percentage of the possible output of the generators, combining the currents produced by various selected generators in predetermined relative proportions, and amplifying the composite current and translating it into sound.

(29) To provide means for compensating for the differences in the energy of the currents produced by the generators of different frequencies.

Other objects are the provision of an electrical musical instrument which may be economically produced in large quantities, in which there is a relatively small number of parts, in which the various elements may be readily assembled, and which will be durable.

Further objects will appear from the following description, reference being had to the accompanying drawings, in which:

Fig. 1 is a plan view of the instrument;

Fig. 2 is a horizontal sectional view showing the pedal keyboard and swell pedal;

Fig. 3 is a vertical cross-sectional view of the upper and lower manuals and the generator assembly;

Fig. 4 is an enlarged vertical sectional view of the assembly of the generators;

Figs. 5, 5a and 5b together constitute a plan viewof the assembly of generators and the synchronous motor for driving the same, various sections and the flexible coupling connecting the countershaft sections;

Fig. 10 is a fragmentary sectional view taken on the line 10-10 of Fig. 8;

Fig. 11 is a right side elevation of the synchronous motor, various parts associated therewith being broken away to show detail, the view being taken substantially on the plane of line 11-1l of Fig. 6;

Fig. 12 is a vertical sectional view-of the synchronous motor taken on the line 1 2-12- of Fig. 6;

Fig. 13 is a fragmentary plan view of a section of multiple contact switches, parts thereof being shown in fragmentary section;

14 is a fragmentary vertical sectional view taken on, the line 14-14 of Fig. 13;

Fig. 15 is a fragmentary sectional view illustrating the method by which the switch contact members are mounted;

Fig. 16 is a fragmentary sectional view taken on the line 16--16 of Fig. 13, illustrating the means by which the switch actuator is connected to the switch contact members;

Fig. 17 is a transverse sectional view taken on the line 17-17 of Fig. 13;

Fig. 18 is a vertical sectional view of the timbre selector mechanism;

Fig. 19 is a sectional -view taken on the line 19-19 of Fig. l8;'

Fig. 20 is a vertical sectional view of the pedal keyboard taken on the line 20--20 of Fig. 2;

Fig. 21 is a plan view of a portion of the pedal keyboard with the pedals removed;

Fig. 22 is a vertical sectional view of the swell pedal and associated mechanism taken on the line 22-22 of Fig. 23;

Fig. 23 is a vertical sectional view of the swell pedal mechanism taken on'the line 23-28 of Fig. 22;

Fig. 24 is a vertical sectional view of the stop 'key operated pre-set combination selector;

Fig. 25 is a fragmentary plan view of the mechanism shown in Fig. 24,- various parts be-- ing broken away to show the details of construction;

Fig. 26 is a vertical sectional view of the instrument taken just inside the right-hand side wall and showing the general arrangement of v the mechanism Figs. 27' and 27a, together constitute a schematic wiring diagT J of the instrument; and

Figs. 28 and 28a constitute a chart usable in conjunction with the wiring diagram to indicate the connections not shown in the diagram and setting forth the numbers of teeth, etc., in the various gearing utilized to drive-the generators.

General description The detailed description of the instrument of my invention will, I believe, be more readily understood if it is read with a previous general 

